Development of experimental Vibro-acoustic transfer function for a system with impact

Abstract

Systems with combined sliding-rolling contacts such as cam-follower, clutches, and gearbox are prone to have clearance(s) as per the design and/or due to manufacturing imperfections or wearing as a result of sliding between components. This clearance non-linearity results in an impact between components, which in turn generates a significant rattle during operation. The noise generation mechanism in rattle is a strong function of impact-velocity and contact forces. The objective of this study is to develop an experimental transfer function to quantify the vibro-acoustics of a cam-follower system with clearance non-linearity. Contact between the cam and the follower is lubricated to minimize the sound generated due to friction. Follower acceleration, reaction forces, and acoustic pressure are measured on a cam-follower setup with combined rolling-sliding contact during impacts under various conditions. Velocity and contact forces are back-calculated using measured signals and the analytical model dynamics. Transfer functions relating the acoustic pressure to velocity and contact forces are estimated in the frequency domain. These transfer functions provide insights into the vibro-acoustic system and can be directly used in conjunction with dynamics models. The output of the study can be used in designing quieter systems with impact.